1. Field of the Invention
The present invention relates generally to robotic devices and methods for inspecting and mapping the interior of pipes and pipe networks, and, more specifically, the present invention is directed to autonomous pipe inspection robots that navigate through pipe networks gathering image data for forming a complete picture of the network, and methods for utilizing the same.
2. Description of the Background
The oldest pipes in the United States date to the late 1800's, and the average non-rehabilitated water and sewer pipe is more than 50 years old. However, depending on the type of material used, pipe operating life ranges from only 50 to 125 years. Much of the existing pipe, therefore, needs to either be replaced or rehabilitated (relined or otherwise repaired) in short order.
A major problem in the U.S. sewer systems is inflow and infiltration (“I&I”). I&I is caused by the inflow of rainwater into the sewer system due to heavy rains and/or the fact that many sewer lines lie below the water table. I&I increases costs at sewage treatment plants, and, in a number of cases, the additional water injected during a rainstorm outstrips the capacity of treatment plants. This often results in the diversion of raw sewage into rivers and streams.
Along the same lines, the biggest problem in the U.S. potable water system is leaky pipes. For example, estimates hold that 35% to 50% of drinking water in the U.S. is unaccounted for once it leaves a water treatment facility, the vast majority of which is lost through leaky pipes. The urgent need to rehabilitate water pipes exists to reduce water leakage from the system, reduce costly emergency break repairs and increase water quality at the consumer's tap.
Government regulation is also increasing in these areas. In June 1999, the GASB (Government Accounting Standards Board) issued “Statement 34” requiring state and local governments to report the value of their infrastructure assets such as buried pipes, storm sewers, bridges and roads. Additionally, the EPA is actively pursuing consent decrees—forcing cities to eliminate sewage overflow into rivers and other bodies of water during heavy rainfalls and to increase water quality nationwide. Finally, the Safe Drinking Water Act, first passed in 1974, requires municipal water suppliers to guarantee that the water quality at the tap is the same as the water quality at the purification plant. The decay, sediment and leakage taking place in either water pipes or water storage tanks accounts for impurities in drinking water that enter the system after the water leaves the water purification plant, and prevents the satisfaction of these government regulations.
In general, the three main functions required to maintain our piping infrastructure are: (1) cleaning; (2) inspecting; and (3) rehabilitating. Cleaning involves the removal of obstructions and debris that blocks the flow of water and sewage. Inspecting involves mapping the pipe interior, characterizing the pipe's defects, and developing a maintenance plan for the pipe. Rehabilitating the pipe involves maintaining and fixing faulty piping.
In total, there are over 1.2 million miles of sewer pipe in the United States. Over time these pipes deteriorate—the pipes crack and corrode and the pipe joints become dislodged—requiring replacement or refurbishment. Traditionally, pipes have been replaced, repaired or refurbished using “trenched” methods. In trenched methods, the land above the targeted pipe is removed along its entire length, typically with an excavator. This often requires closing a roadway and removing the earth and pavement underneath it, which is later replaced at great cost.
Alternatively, in trenchless methods the pipe is accessed via manholes—or in some instances by digging access holes at both ends of the pipe—and is repaired/refurbished via relining or grouting. In most cases, trenchless technology completely eliminates the need to dig up roads and land and is significantly less expensive. As a result, trenchless methods are rapidly gaining market share and are becoming the preferred methods in the U.S. and throughout the world. Generally, old trenched methods are still employed only when specification engineers are not trained in trenchless methods or the subject pipe is so deteriorated it requires the dig and replace method (which is only required a small percentage of the time).
Although they are gaining momentum, traditional (i.e., current) trenchless pipe rehabilitation methods are quite limited. For example, contractors currently use dedicated trucks equipped with remote controlled video capture systems typically mounted on small wheeled or tracked platforms. Such systems typically cost over $100,000 and are highly specialized to the task. These mobile camera platforms trail a wire tether to bring control signals and power for the platform motors and camera from the truck, and to return video signals to be recorded on tape in the truck. The operator directs the view of the camera and the forward motion of the platform that carries it. During the process of inspecting, the operator continuously views the image, stopping to classify features such as laterals, and defects in accordance with descriptive industry standards. The efficiency of this approach is limited by the embedding of the classification process and the platform controls within the task of collecting video data. There is also a high degree of variability in the classification results depending on the skill and experience of the operator.
New robotic devices and methods are continually sought to address these and other limitations of the prior art. Specifically, robotic devices that can perform inspection and surveillance of subterranean or otherwise located pipes that are difficult to access without the need for extensive operator interaction are greatly desired. The present invention, in its many preferred embodiments addresses these and other limitations of the prior art.